[LyX/2.1.x] Fix #9490: SIGSEGV involving LyX macros --- A reproducible MWE (part II)

[Enrico Forestieri]

commit bc79c9a27b7c752d3fe82939ae29b88950337e61
Author: Enrico Forestieri <for...@lyx.org>
Date:   Mon Oct 5 22:43:20 2015 +0200

    Fix #9490: SIGSEGV involving LyX macros --- A reproducible MWE (part II)

diff --git a/src/mathed/MathMacro.cpp b/src/mathed/MathMacro.cpp
index bc942be..43892f6 100644
--- a/src/mathed/MathMacro.cpp
+++ b/src/mathed/MathMacro.cpp
@@ -63,6 +63,8 @@ public:
        ///
        void setOwner(MathMacro * mathMacro) { mathMacro_ = mathMacro; }
        ///
+       MathMacro * owner() { return mathMacro_; }
+       ///
        InsetCode lyxCode() const { return ARGUMENT_PROXY_CODE; }
        ///
        void metrics(MetricsInfo & mi, Dimension & dim) const {
@@ -138,6 +140,7 @@ MathMacro::MathMacro(Buffer * buf, docstring const & name)
 MathMacro::MathMacro(MathMacro const & that)
        : InsetMathNest(that), expanded_(that.buffer_)
 {
+       setBuffer(*that.buffer_);
        assign(that);
 }
 
@@ -175,16 +178,45 @@ void MathMacro::assign(MathMacro const & that)
                ArgumentProxy * p = dynamic_cast<ArgumentProxy 
*>(expanded_.cell(0)[i].nucleus());
                if (p)
                        p->setOwner(this);
+
+               InsetMathNest * ni = 
expanded_.cell(0)[i].nucleus()->asNestInset();
+               if (ni)
+                       updateNestedChildren(this, ni);
        }
-       if (macro_ && lyxrc.preview == LyXRC::PREVIEW_ON) {
-               // As MathData::metrics() is not called when instant preview is
-               // on, we have to update macro_ by ourselves. In this case, we
-               // simply let it point to the last known good copy of MacroData.
+       if (macro_) {
+               // The macro_ pointer is updated when MathData::metrics() is
+               // called. However, when instant preview is on or the macro is
+               // not on screen, MathData::metrics() is not called and we may
+               // have a dangling pointer. As a safety measure, when a macro
+               // is copied, always let macro_ point to the backup copy of the
+               // MacroData structure. This backup is updated every time the
+               // macro is changed, so it will not become stale.
                macro_ = &macroBackup_;
        }
 }
 
 
+void MathMacro::updateNestedChildren(MathMacro * owner, InsetMathNest * ni)
+{
+       for (size_t i = 0; i < ni->nargs(); ++i) {
+               MathData & ar = ni->cell(i);
+               for (size_t j = 0; j < ar.size(); ++j) {
+                       ArgumentProxy * ap = dynamic_cast
+                               <ArgumentProxy *>(ar[j].nucleus());
+                       if (ap) {
+                               MathMacro * mm = ap->owner();
+                               if (mm->macro_)
+                                       mm->macro_ = &mm->macroBackup_;
+                               ap->setOwner(owner);
+                       }
+                       InsetMathNest * imn = ar[j].nucleus()->asNestInset();
+                       if (imn)
+                               updateNestedChildren(owner, imn);
+               }
+       }
+}
+
+
 Inset * MathMacro::clone() const
 {
        MathMacro * copy = new MathMacro(*this);
diff --git a/src/mathed/MathMacro.h b/src/mathed/MathMacro.h
index 239495e..c7c155c 100644
--- a/src/mathed/MathMacro.h
+++ b/src/mathed/MathMacro.h
@@ -162,6 +162,9 @@ private:
        bool editMode(BufferView const * bv) const;
        /// Copy all members (except base class members)
        void assign(MathMacro const &);
+       /// Recursively update the pointers of all expanded macros
+       /// appearing in the arguments of the current macro
+       void updateNestedChildren(MathMacro *, InsetMathNest *);
        
        /// name of macro
        docstring name_;
diff --git a/status.21x b/status.21x
index 6f343fc..e5038f7 100644
--- a/status.21x
+++ b/status.21x
@@ -70,6 +70,8 @@ What's new
 
 * USER INTERFACE
 
+- Fix crash when unfolding/copying macros containing other macros (bug 9490).
+
 - Fix automatic insertion of longtable captions (bug 9692).
 
 - Fix setting of nested minipage via the dialog (bug 8716).